Rotary switch



C. E. HAMMER ROTARY SWITCH May 3, 1949.

Filed Aug. 9, 1946 Charles E. Hummer IN VEN TOR.

PATENT ATTORNEY FIG. 3

Patented May 3, 1949 2,468,974 ROTARY SWITCH Charles E. Hammer, Hagerstown, Md., assignor to Fairchild Engine and Airplane Corporation, a corporation of Maryland Application August 9, 1946, Serial No. 689,390

8 Claims.

The present invention relates to rotary switches and more particularly to improved means for limiting the travel of electrically controlled equipment.

A primary object of the present invention is the provision of a rotary type lim t switch which can be utilized as a dependable and reliable switching means for limiting the travel of electric equipment, controlling the operation of electrical apparatus, indicating the position of movable members and for other similar uses. It is a further object to provide a rotary limit switch which is sealed against dirt and moisture and which will operate satisfactorily underwide variations in temperature, moisture and other climatic conditions. A further object resides in the provision of a limit switch of the multiple or gang type which is of flexible construction and capable of being readily converted as to the number of contained switch units without material alteration to the switch construction.

A further object of the present invention resides in the provision of a rotary limit switch which is readily accessible without its removal from the mounting panel and which can be serviced and adjusted without the necessity of mechanical or electrical disconnections. It is a further object to provide in such an improved switch construction an arrangement in which the cams are individually adjustable to provide any desirable sequence of operation of the respective switches and one in which the cam positions are positively maintained during continued operation. A further object is to provide a multiple limit switch in which the individual units are readily interchangeable without the necessity of Fig. 2 is a cross-sectional view as taken along' the lines 2--2 of Fig. 1;

Fig. 3 is a perspective view from the rear with the casing partially broken away to show the interior mechanism;

the mounting end of the switch assembly;

Fig. 5 is a cross-sectional detail showing thev seal formed in the casing assembly; and

Fig. 6 is a detailed plan view of one of the switch actuating levers.

The housing for the present switch construction is formed by the cylindrical shell or casing l0 closed at each end by the apertured plates or covers II and I2. An actuating shaft l3 extends through an opening in the mounting plates II in which it is suitably journaled at llb. Each end plate H and I2 is suitably rabbeted, as at Ila in Fig. 5, to receive an annular sealing gasket or washer H! by which the joints between the casing shell 10 and the end plates are made tight against air and moisture. Each end plate H and I2 is suitably apertured to receive a plurality of threaded studs l4. I5, l6 and H, in such manner that the nuts Ma, l5a, l6a and "a tightened upon the protruding threaded portions of the respective studs serve to maintain the end plates in a clamping and sealed engagement with the intermediate shell 10. It will be understood that certain of these threaded studs may be made sufficiently long to project beyond the surface of the end plate II a suitable distance to serve as at-- tachment bolts for mounting the switch assembly upon a panel or other supporting structure. The studs Ill and I! have been found satisfactory for this purpose and the mounting panel would of course be suitably apertured to permit the passage therethrough of the actuating shaft l3 and the threaded outlet IQ for the electrical wiring 20.

The actuating shaft I3 is preferably of substantial diameter or size and would carry a suitable actuating lever or other means for rotating the shaft and the internal mechanism attached thereto, depending upon the particular application of the switch. The location of the actuating shaft l3 and electrical outlet 19 on the same or mounting end of the switch assembly permits access to the interior of the switch c'asing from the remote end I2 without the necessity of making mechanical or electrical disconnections, and allows servicing or adjustment of the switch mechanism without the removal of the assembly from the mounting panel.

A plurality of snap action insert type or microswitches S 1, S2 and S3 are held in position within the switch casing by means of the threaded studs l5 and I6. These micro-switches are of a well known available type and it is not considered necessary to describe them in further detail other than to state that their actuating contacts are cam shaft l3.

disposed at 33 at the upper facc of each switch unit. The present multiple or gang type rotary switch construction is adapted for use with one or more micro-switch units of the type indicated at Si being held in position by the nuts threadedly adjustable upon the studs [5 and I8, up to five of such switch units having been used satisfactorily in the same switch assembly. The actuating shaft i3 has a reduced diameter portion within the housing beyond the thrust bearing I lb and has freely mounted thereon the cam elements Cl, C2 and C3. Each cam has an enlarged cylindrical body portion co-axially mounted upon the shaft I3 and is provided with radial teeth or serrations 3|.

Upon the threaded studs N there are mounted a corresponding number of switch actuating levers Ll, L2 and L3, intermediately spaced by the spacers 24 and rotatably retained upon the unthreaded portion of the stud I by means of suitable lock nuts, such that each lever L is disposed in the same transverse plane as that of the corresponding cam portion of each cam C. As shown in the detail view of the switch lever L in Fig. 6, the free end of each lever is apertured as at 22 to receive the terminal of a tension spring 21 anchored at its other terminal to the stud l1 and arranged to draw. the lever toward the cam C and its shaft IS. The opposite end of each switch lever is provided with a suitable bore 23 which is pivotally mounted upon the stud I4 and an intermediate portion is provided with the adjustable contact screw 25 which is resiliently retained at its adjusted position by the spring detent 25a.

Fixedly mounted upon the cam shaft l3, as by keys, set-screws or other suitable means, there are serrated cam engaging cylindrical elements 30 engaging the serrated faces 3| of the corresponding cams Cl, C2 and C3 in a rigidly fixed relationship therewith when the end nut is drawn up tightly on the threaded end portion of the A plurality of radial holes 32 are provided in each of the cams C by which a pin, spanner wrench or other tool may be inserted to rotate the respective cam when the nut has been backed away sufilciently to permit clearance of the serrations, or for holding one cam while adjusting another. It will accordingly be noted that the positions of the cam C on the main actuating shaft l3 are individually adjustable, so that any desired sequence of operation of the switch units S is obtainable. These relative positions of the cams are positively maintained by the serrations 31 at the end faces of the cams C and the cam backing elements 30. As shown in Fig. 4 an access hole or opening ifla is provided in the shell or wrapper casing ID to facilitate servicing and adjustment of the internal switch mechanism. A ring clamp or cover band 28, which is adjusted by the bolt 29, is slidable along the shell casing to selectively open or close the access opening lOa. Tightening of the bolt 29 in the closed position of the cover band 28 provides a relatively tight and immovable closure for the access opening. The individual micro-switch units 8 may also be readily changed by removal of the back plate l2 and sliding of the switch units along the supporting studs i5 and It, without the necessity of any readjustment of the cams C or their respective levers L.

The operating shaft [3 may be rotated in either direction by means of a lever arm, crank or other means" (not shown) which is fixed thereto in order, to actuate in the desired sequence the switch units S, a pretravel of some 240 and an overtravel of about being available. In certain applications where a spring return may be desirable a flat coil spring 28 is pivotally attached to the spring anchor 21 at its outer terminal, and attached to the actuating shaft I! at its inner terminal, being adapted to return the cams in either direction of rotation of the actuating shaft [3. Other forms and modifications of the disclosed switch construction which may occur to those skilled in the art after a reading of the present description, both with respect to its general arrangement and the details of its respective parts, are intended to come within the scope and spirit of the present invention as more particularly set forth in the appended claims.

I claim:

1. A limit switch construction including an apertured mounting plate, attachment means engageable with certain of said apertures for attaching said mounting plate to a supporting structure, a plurality of threaded studs engaging apertures in said mounting plate and supported thereby in a parallel relationship to each other normal to said mounting plate, a plurality of micro-switch units slidingly mounted upon a pair of said parallel threaded studs, a plurality of switch actuating levers pivotally mounted upon a further one of said studs, an actuating cam shaft rotatably supported within said mounting plate having its axis disposed parallel to said threaded studs and eccentrically disposed with respect to said pair of switch supporting studs, and a plurality of cam elements adjustably mounted upon said actuating cam shaft arranged for individual actuation of said switches, said cam elements having serrated end surfaces arranged to positively maintain relatively adjusted positions to which each is adjusted without removal of the adjacent cam elements, said actuating levers and cam shafts each separately mounted from and forming no part of said micro-switch units, said switch units being slidably removable along said pair of supporting studs without the necessity of removal or change in adjustment of said cam elements or said switch actuating levers.

2. A limit switch construction including an apertured mounting plate, a plurality of threaded studs engaging apertures in said mounting plate and supported thereby in a parallel relationship to each other and normal to said mounting plate, a plurality of micro-switch units slidingly mounted upon a pair of said parallel threaded studs, a plurality of switch actuating levers pivotally mounted upon a further one of said threaded studs, a cam actuating shaft rotatabiy supported within said mounting plate having its axis disposed parallel to said threaded studs and eccentrically disposed with respect to said pair of switch supporting studs, and a plurality of cam elements adjustably mounted upon said actuating cam shaft arranged for theindividual actuation of said switches, a cylindrical casing member engaging the rear face of said mounting plate, an end closure disc engaging the opposite end of said cylindrical closure member, said end disc being apertured to receive certain of said threaded studs, fastening means engaging the ends of said studs for clampingly retaining said cylindrical casing member between said end disc and said mounting plate arranged for the ready removal thereof and access to said switch units, said actuating levers and cam shaft each separately mounted from and forming no part of said microswitch units, and serrated and surfaces on said cam elements arranged to positively maintain reiatively adjusted positions to which each is adjusted without removal of the adjacent cam elements, said switch units being slidably removable along said pair of supporting studs without the necessity of removal or change in adjustment of said cam elements or said switch actuating levers.

3. A switch operating mechanism including a supporting framework, a mounting plate, a housing removably supported upon said framework and said mounting plate, a micro-switch removably supported from said framework within said housing, said switch having an operating contact pin, a lever arranged for the actuation of said contact pin pivotally supported on said framework within said housing, a spring interconnecting said framework with the free end of said lever urging an intermediate portion of said lever into contact with said pin, contact means carried by said lever including an integrally headed contact screw threadedly mounted upon said lever, said contact screw having a shank terminal arranged to engage said contact pin, resilient means engaging the head of said contact screw for retaining the same in its threadedly adjusted position, and cam means rotatably mounted upon said mounting plate for actuation from without said housing arranged to engage the said lever under the influence of said spring.-

4. In a multiple switch construction, an apertured mounting plate, threaded means extending through apertures in said mounting plate arranged for the attachment of said mounting plate to a supporting structure, an actuating shaft passing longitudinally through and journalled within said mounting plate, cam elements adjustably mounted upon said actuating shaft, said cam elements having serrated end surfaces arranged to positively maintain relatively adjusted posi tions to which each is adjusted without removal of the adjacent cam elements, spring-pressed levers pivotally supported from said mounting plate adapted for limited rotation within longitudinally spaced transverse planes for engagement with said respective cam elements, and a plurality of micro-switch units supported from said mounting plate arranged for individual actuation of said respective lever elements initiated by rotation of said actuating shaft and its attached cam elements.

5. In a switch construction adapted for combining a plurality of like micro-switches to form a multiple switch, the combination comprising an apertured mounting plate, threaded means extended through apertures in said mounting plate arranged for the attachment of said mounting plate to a supporting structure, an actuating shaft passing through and journaled within said mounting plate, cam elements having serrated end faces adj ustably mounted in the rotative sense upon said actuating shaft without disturbing the adjustment of each other, a plurality of longitudinally spaced rod elements supported from said mounting plate, a plurality of spring-pressed levers pivotally supported from one of said rod members arranged for rotation within longitudinally spaced transverse planes for engagement with said respective cam elements, a plurality of micro-switch units supported from another of said rod members arranged for individual actuation by said respective levers initiated by rotation of said actuating shaft and said adjustably attached cam elements, threaded means engaging the free terminal of said actuating shaft for clamping the said serrated end face cam elements thereon in their adjusted positions, and recesses 6 formed within said cam elements arranged to facilitate their rotation about said actuating shaft to their adjusted positions upon the release of said threaded means.

6. A moisture-tight casing construction for a switch mechanism including an apertured mounting plate, threaded stud means engaging certain apertures in said mounting plate arranged for the attachment of the front face of said mounting plate to a supporting structure, attachment means for attaching the switch mechanism against the rear face of said mounting plate, said mounting plate having a rabbeted portion on a back face thereof, a gasket in engagement with said mounting plate rabbeted portion, a casing member engaging said gasket in said rabbeted portion of said mounting plate at the near and of said casing member, an end closure disc having a rabbeted portion, a gasket engaging said rabbeted portion arranged to engage with said end closure disc the far end of said closure member in a moisturetight relationship, said end disc apertured to receive certain of said threaded stud means, and fastening means engaging certain of said threaded studs for olampingly retaining said casing member against the gaskets between said end disc and said mounting plate in a moisture-tight relationship arranged to permit ready removal of said end disc and said casing member for access to the enclosed switch mechanism without the necessity of removing said mounting plate from the supporting structure.

7. A casing construction for housing a switch mechanism including an apertured mounting plate, fastening means engaging certain apertures in said mounting plate arranged for the attachment of the front face of said mounting plate to a supporting structure, attachment means engaging certain apertures in said mounting plate arranged for the attachment of a switch mechanism to the rear face of said mounting plate, said mounting plate having a peripherally recessed portion on the back face thereof, a casing member engaging said peripherallyrecessed portion in said mounting plate at a near and of said casing member, an end closure disc engaging the far end of said closure member, said far end disc apertured to receive certain of said fastening means, retaining means engaging said fastening means for clampingly retaining said casing member between said end disc and said mounting plate, and electrical conductor means passing through an apertured portion of said mounting plate for connection to the switch mechanism arranged to permit ready removal of said end disc and said casing member for access to the enclosed switch mechanism without the necessity of removing said'mounting plate from the supporting structure, the switch mechanism from the plate or disconnecting the electrical connections to the switch mechanism.

8. In a multiple switch construction, a switch supporting assembly, a plurality of switch units supported from said assembly arranged for individual actuation, a plurality of switch actuating levers pivotally supported upon said assembly and operatively associated with a respective switch unit, an actuating shaft journalled within said supporting assembly, a plurality of cam elements mounted upon said actuating shaft having cam faces engageable with said levers for their actuation, said cam elements having end faces arranged to engage the corresponding end faces of the adjacent cam elements arranged to positively maintain the relatively adjusted posi- 2,468,974 7 8 tions to which each cam element is adjusted REFERENCES CITED without the necessity of removal of the adjacent cam elements, means for locking said cam elei fgig g gg are of record in the ments in engagement with each other and in a pa fixed relationship to said actuating shaft and UNITED STATES PATENTS means for rotating an individual cam element into an adjusted position upon said actuating shaft figg i i upon release of said locking means and axial 13588o9 1920 separation of the adjoining cam elements without 2 Kerwin Jul 1924 the necessity of disturbing the adjustment of said 10 2181829 Jamey 1939 Jacent cam elements' 2,243,566 Kimball May 37: 1941 CHARLES HAMMER- 2,s19,50a Glogau May 18, 1943 

